Now, smugglers say their trade has become much more difficult and dangerous.

The trade in sugar cane and spices was becoming profitable.

By the late 1800s, the trade of Passenger Pigeons had become commercialized.

In addition, international trade became less focused on cultural exchanges and instead was seen as a necessity for the growth of the Chinese economy.

Now, regional trade and investment have become increasingly important.

But trade is becoming a divisive issue, especially since the end of the war.

The trade became the emblem of everything wrong with the Mets.

With American automakers taking a proactive stance in government and private industry efforts on vehicle recycling, the cash-for-cars trade has become more lucrative than ever.

"The trade has become much more sophisticated," Ms. Davies said.